From my understanding its important to get an alignment after altering the suspension in any way.

I have 09 CrewCab....without the three leafs in rear, I set my 5100 on first setting .85 I think, the truck ended up level. If you go with second setting, your front end will be higher,,,,,,,bought a camper shell, set on the truck, and front is about 1/2 inch higher than rear.....this is on first setting....FYI

do you have extended and collapsed lengths for this shock by chance? thanks.

Sure do

Rear shock Part #24-214667 will work with a 2" or 2.5".
Bilstein 5125 series 24-214667 Dimensions:Note(90 day warranty on 5125 series from original date of purchase)
Valving: 170/60
Extended Length: 25.98"
Collapsed Length: 16.14"

I'm in the same boat as 1nonlygarcia. I want to buy all 4 shocks and install them. What else do I need?

This kit is straight forward, you do not need any other parts. You will need a wall mounted spring compressor in order to remove the coils off the stock strut assembly, then insert the new 5100. Or have a shop that has the equipment and has this tool do it for you, other than that, it is 3 bolts on top of the strut and on at the bottom. As far as parts, you are good to go with just the 4 shocks. Set the fronts at the desired lift height you are looking to obtain and install the rears.